Start-up billet head for a continuous casting machine for metal, in particular, steel

ABSTRACT

A start-up billet head for a continuous casting machine for metal closes off an outlet of the casting die before start-up of the casting process. The start-up billet head has a coupling part facing an interior of the casting die and forms together with a billet cast in the casting die a positive-locking, hook-shaped connection. The connection can be decoupled after leaving the casting die by performing a tilting movement of the start-up billet head about a joint of the start-up billet. The coupling part has a recess with a first side active in a billet removal direction and a second side facing the first side. The first and second sides have oppositely oriented arc shapes. The coupling part has the shape of a preliminary billet profile with at least one undercut located in the area of at least one flange or angled joint of the preliminary billet profile.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a start-up billet head for a continuouscasting machine for casting metal, in particular, steel. The start-upbillet head closes off the outlet of the continuous casting die beforestarting up the casting process. The start-up billet head comprises acoupling part facing the interior of the casting die which together withthe cast billet forms a positive-locking, hook-shaped connection which,after leaving the continuous casting die, can be decoupled by a tiltingmovement of the start-up billet head about a joint of the start-upbillet wherein the hook-shaped coupling part on the side that is active(i.e., acts on the billet to be removed) in the billet removal directionis undercut with an arc shape and on the opposite side has an arc shapethat is oriented opposite to the arc shape of the undercut.

[0003] 2. Description of the Related Art

[0004] Such a start-up billet head is known from DE 38 10 304 C1. Suchstart-up billet heads serve to convey at the beginning of the castingprocess the steel solidified within the continuous casting die in thearea of the coupling part by means of a start-up billet and a drivingdevice. The start-up billet head forms thus a detachable couplingbetween the leading end of the cast billet and the start-up billet. Assoon as the start-up billet head has passed through the driving device,the driving device can thus transmit the removal forces onto the castbillet itself and the start-up billet must be decoupled via the start-upbillet head. The phase of transmission of the removal forces onto thestart-up billet head and from it onto the casting strand depends on towhich degree the coupling can already receive forces. The take-up of theremoval forces depends on the configuration of the start-up billet head.The configuration of the start-up billet head, however, depends also onthe cast billet profile. It is therefore not possible to employ theknown start-up billet head in connection with all cast cross-sectionsand all dimensions of the cast billet.

SUMMARY OF THE INVENTION

[0005] It is an object of the present invention to provide a start-upbillet head which can be employed in connection with especially complexbillet cross-sections and thus continuous casting die cross-sectionssuch that at the beginning of the casting process sufficiently highremoval forces can be transmitted onto the cast billet.

[0006] In accordance with the present invention, this is achieved inthat for a continuous casting die for a preliminary billet profile thecoupling part has at least one undercut in the area of a flange or anangled joint of a preliminary billet profile. This makes it possible toengage complex billet cross-sections with weak stay parts such that asufficiently high removal force during start-up can be transmitted ontothe billet profile in that the flange part or the angled joint take onas much as possible of the removal force.

[0007] The principle of the invention can be applied according tofurther features, for example, such that for a double-T billet profilein both flanges of the preliminary billet profile undercuts aresymmetrically arranged. The cross-sections and dimensional widthsavailable within the flanges make it possible to transmit the requiredmagnitude of removal force onto the solidifying cast billet.

[0008] According to other features, it is provided that the undercutextends, beginning parallel at the stay of the preliminary billetprofile and then following the transition between the stay and theflange, with a certain proportion of the thickness of the flange withinthe flange. The flange thickness can thus be used in a beneficial wayfor the removal force transmission.

[0009] According to another embodiment it is suggested that on theactive side of the hook-shaped coupling part a flange wall is formedwhose wall surface extends to the area of the undercut. The cast metalfills thus the space at the location of the large cross-section of theflange so that in the case of preliminary billet profiles considerablygreater removal forces can be transmitted.

[0010] In this connection, it is advantageous that the flange wall has athickness which corresponds approximately to half the thickness of theflange in the preliminary billet profile. By using half the thickness itis possible to utilize as much as possible the cross-section availablefor the removal force transmission.

[0011] Moreover, it is possible to advantageously use the principle thatwith reduced thickness of the stay of the billet profile the undercut orundercuts are limited to the flange or the flanges of the preliminarybillet profile. In this way, it is thus also possible to castpreliminary billet profiles with thinner stays without the removal forcetransmission suffering thereby.

BRIEF DESCRIPTION OF THE DRAWING

[0012] In the drawing:

[0013]FIG. 1 is a longitudinal section of the continuous casting diewith start-up billet head; and

[0014]FIG. 2 is a front view of the start-up billet head viewed in theremoval direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] According to FIG. 1, the start-up billet head is to be used for acontinuous casting machine for metal, in particular, steel. The start-upbillet head closes off the outlet 1 a of the continuous casting die 1before the beginning of the casting process by means of the couplingpart 2 facing the interior 1 b of the casting die which coupling part isarranged so as to seal the die. The coupling part 2 forms together withthe cast liquid metal, which quickly solidifies, the positive-lockinghook-shaped connection 3 which, after the cast billet has left the die,can be decoupled, i.e., released, at a location downstream of a removaldevice by a tilting movement of the start-up billet head about a joint 4of the start-up billet 5. For this process, the hook-shaped couplingpart 2 has a recess with an arc shape at the side 7 which is active inthe billet removal direction 6 (acts on the billet to be removed, i.e.,transmits removal forces). The opposite side 8 of the recess is providedwith an oppositely oriented arc shape.

[0016] For applying this principle on a so-called continuous casting diefor preliminary billet profiles in which preliminary billet profiles,for example, double-T sections, angled sections or U-sections are cast,it is advantageous that the coupling part 2 has at least one undercut 9in the area of a flange 10 or an angled joint of a billet profile 11(FIG. 2). In the illustrated double-T billet profile 11 a the twoflanges 10 of the billet profile 11 have undercuts 9 schematicallyarranged therein (FIG. 2). Accordingly, higher removal forces can betransmitted at these locations, even when thinner stays 12 are present.

[0017] The undercut 9 begins at the stay 12 of the billet profile 11 andextends parallel to the stay and then follows the transition 13 betweenthe stay 12 and the flange 10 with a certain preset proportion 14 of thethickness 10 a of the flange 10, respectively. On the active side 7 ofthe hook-shaped coupling part 2 a flange wall 15 is formed whose wallsurface 15 a continues into the area of the undercut 9. As an example,it is shown that the flange wall 15 has a thickness 15 b whichcorresponds approximately to half the thickness 10 a of the flange 10the billet profile 11. In principle, with decreasing thickness 12 a ofthe stay 12 of any suitable billet profile, the undercut 9 or theundercuts 9 can be limited to the flange 10 or the flanges 10 of thepreliminary billet profile.

[0018] While specific embodiments of the invention have been shown anddescribed in detail to illustrate the inventive principles, it will beunderstood that the invention may be embodied otherwise withoutdeparting from such principles.

What is claimed is:
 1. A start-up billet head for a continuous castingmachine for metal, wherein the start-up billet head is configured toclose off an outlet of a continuous casting die before start-up of thecasting process; the start-up billet head comprising: a coupling partfacing an interior of the casting die configured to form together with abillet, that is cast in the casting die, a positive-locking, hook-shapedconnection, wherein the connection is configured to be decoupled afterleaving the casting die by performing a tilting movement of the start-upbillet head about a joint of the start-up billet; the hook-shapedcoupling part having a recess with a first side active in a billetremoval direction and a second side facing the first side; the firstside of the hook-shaped coupling part having an arc shape and the secondside having an arc shape oriented opposite to the arc-shape of the firstside; the coupling part having a shape of a preliminary billet profileand comprising at least one undercut configured to be located in thearea of at least one flange or at least one angled joint of thepreliminary billet profile.
 2. A start-up billet head according to claim1, wherein the preliminary billet profile is a double-T profile havingtwo flanges and a stay connecting the flanges, wherein the two flangesof the billet profile are provided with one of the undercuts,respectively, and wherein the undercuts are symmetrically arranged.
 3. Astart-up billet head according to claim 1, wherein the at least oneundercut begins parallel to a stay of the preliminary billet profile andthen follows a transition between the stay and the flange of thepreliminary billet profile end extends within the flange with a certainproportion of the thickness of the flange.
 4. A start-up billet headaccording to claim 1, wherein on the active side of the hook-shapedcoupling part a flange wall is formed whose wall surface extends intothe area of the undercut.
 5. A start-up billet head according to claim4, wherein the flange wall has a thickness which correspondsapproximately to half the thickness of the flange.
 6. A start-up billethead according to claim 1, wherein the preliminary billet profile has astay connected to the flange and wherein, with decreasing thickness ofthe stay of the billet profile, the at least one undercut is limited tothe at least one flange or angled joint of the preliminary billetprofile.